This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Assembly of transmembrane (TM) proteins is a fundamental aspect of cell physiology and disease. For example, the protein translocon, an essential component of the biosynthesis pathway for many proteins in all organisms, consists of several intramembrane and soluble protein subunits. Experiments and theory have provided valuable insight into the role of specific protein amino acids in membrane protein assembly;for example, the WxxW motif drives dimerization of TM helices (Sal-Man et al, 2007). But the role of the lipid molecules remains obscure. Recent experiments and molecular dynamics (MD) simulations performed in our lab suggest that lipid molecules may participate directly in assembly of membrane proteins. To understand how lipids mediate and stabilize interactions between TM proteins, we propose investigating the ?s dynamics of membrane-embedded TM segments whose oligomerization behavior is being assessed in the lab using molecular biology experiments.